The telephone industry has for many years found it convenient to utilize modular plugs and jacks with which to interconnect telephone handsets and bases as well as associated equipment. Indeed, even keyboards and video display terminals benefit from the use of such modular equipment.
A modular plug performs the task of terminating one or more individual wires within a dielectric housing that conveniently connects to an associated modular jack and provides electrical continuity therebetween. Modular plugs comprise a dielectric housing having a plurality of ducts, each receiving an individual conductor surrounded by a relatively soft insulating material. After insulated conductors are positioned in the dielectric housing, metallic terminals having one or more sharp edges (tangs) at one end are inserted into slots of the housing so as to pierce the insulation and make electrical contact with the conductor. The other end of the terminal comprises a surface adapted to make electrical contact with wires included in a mating jack receptacle.
An early example of such a connecting device is shown in U.S. Pat. No. 3,761,869 issued to Hardesty et al on Sept. 25, 1973. In this patent each terminal includes several pointed blades for penetrating a conductor's insulating material as well as the conductor itself. This technique works quite well with what is known as "tinsel" conductor or with stranded wire; but, certain problems are encountered when solid wire is used; namely, the individual tangs may sever the solid wire during assembly of the plug and, in time, separation may occur causing the electrical path to open.
An insulation piercing contact, designed for use in connection with solid wire, is disclosed in U.S. Pat. No. 4,431,246 issued to J. L. Vaden on Feb. 14, 1984. This patent shows a terminal contact having three tangs with adjacent ones beveled in opposite directions at their bottom edge. When the terminal is properly urged into direct contact with the insulated solid wire, adjacent tangs not only penetrate the insulation but also make contact with the solid wire on opposite sides of its center line. The tangs are beveled at the bottom edge and generally tapered such that they are thinner at the bottom than where they are connected to the upper portion of the terminal. This particular technique also relies on the proper positioning of an insulated conductor for an acceptable electrical connection to be made. It has been found, however, that while beveling and tapering provide some degree of control in assuring a proper connection between metallic terminals and conductors, greater control is desirable.
It is therefore an object of this invention to provide a modular plug for terminating electrical cords having solid wire conductors without severing the wire during assembly.
It is another object of this invention to relax tolerances associated with beveling, tapering and conductor placement in providing consistent, reliable connections between metallic terminals and solid wire conductors.